Limits...
Narrow groove plasmonic nano-gratings for surface plasmon resonance sensing.

Dhawan A, Canva M, Vo-Dinh T - Opt Express (2011)

Bottom Line: We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration.Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems.Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.

ABSTRACT
We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration. This eliminates the angular dependence requirements of SPR-based sensing and allows development of robust miniaturized SPR sensors. Simulations based on Rigorous Coupled Wave Analysis (RCWA) were carried out to numerically calculate the reflectance - from different gold and silver nano-grating structures - as a function of the localized refractive index of the media around the SPR nano-gratings as well as the incident radiation wavelength and angle of incidence. Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems. Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

Show MeSH

Related in: MedlinePlus

(a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove silver nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove silver nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar silver film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar silver film would have the equivalent surface area as would be present in silver nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3368305&req=5

g007: (a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove silver nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove silver nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar silver film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar silver film would have the equivalent surface area as would be present in silver nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.

Mentions: (a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove gold nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove gold nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar gold film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar gold film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar gold film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar gold film would have the equivalent surface area as would be present in gold nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.


Narrow groove plasmonic nano-gratings for surface plasmon resonance sensing.

Dhawan A, Canva M, Vo-Dinh T - Opt Express (2011)

(a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove silver nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove silver nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar silver film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar silver film would have the equivalent surface area as would be present in silver nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368305&req=5

g007: (a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove silver nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove silver nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar silver film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar silver film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar silver film would have the equivalent surface area as would be present in silver nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.
Mentions: (a-d) RCWA calculations showing reflectance curves (differential reflectance in blue, reflectance curves with localized refractive index around the grating n = 1.33 in green and with n = 1.53 in red) for a narrow groove gold nano-grating - with 100 nm periodicity and 7 nm groove width - for a 1 nm binding of target (refractive index = 1.53) on the surface of the metallic film. The effect of nano-grating height ‘H’ on the reflection spectra is shown for the following values of ‘H’: (a) 50 nm, (b) 150 nm, (c) 200 nm, (d) 250 nm. (e) The effect of nano-grating height ‘H’ on the amplitude of the differential reflectance (peak maxima – peak minima) for different plasmon modes coupling into the narrow groove gold nano-gratings. The dashed red line provides the maximum value of the amplitude of differential reflectance for a planar gold film evaluated using the Kretschmann configuration and wavelength interrogation, while the dashed light green line provides the maximum value of the amplitude of differential reflectance for a planar gold film evaluated using the Kretschmann configuration when the interrogation wavelength is less than 800 nm. The dashed dark green line provides the maximum value of the amplitude of differential reflectance for a planar gold film - evaluated using Kretschmann configuration and employing wavelength interrogation - that is normalized such that the planar gold film would have the equivalent surface area as would be present in gold nano-gratings of height ‘H’, while the dashed blue line provides the normalized value of the maximum amplitude of differential reflectance when the wavelength of interrogation is less than 800 nm.

Bottom Line: We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration.Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems.Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.

ABSTRACT
We present a novel surface plasmon resonance (SPR) configuration based on narrow groove (sub-15 nm) plasmonic nano-gratings such that normally incident radiation can be coupled into surface plasmons without the use of prism-coupling based total internal reflection, as in the classical Kretschmann configuration. This eliminates the angular dependence requirements of SPR-based sensing and allows development of robust miniaturized SPR sensors. Simulations based on Rigorous Coupled Wave Analysis (RCWA) were carried out to numerically calculate the reflectance - from different gold and silver nano-grating structures - as a function of the localized refractive index of the media around the SPR nano-gratings as well as the incident radiation wavelength and angle of incidence. Our calculations indicate substantially higher differential reflectance signals, on localized change of refractive index in the narrow groove plasmonic gratings, as compared to those obtained from conventional SPR-based sensing systems. Furthermore, these calculations allow determination of the optimal nano-grating geometric parameters - i. e. nanoline periodicity, spacing between the nanolines, as well as the height of the nanolines in the nano-grating - for highest sensitivity to localized change of refractive index, as would occur due to binding of a biomolecule target to a functionalized nano-grating surface.

Show MeSH
Related in: MedlinePlus